Vulkan-Docs/chapters/samplers.txt

// Copyright (c) 2015-2019 Khronos Group. This work is licensed under a
// Creative Commons Attribution 4.0 International License; see
// http://creativecommons.org/licenses/by/4.0/

[[samplers]]
= Samplers

[open,refpage='VkSampler',desc='Opaque handle to a sampler object',type='handles']
--

sname:VkSampler objects represent the state of an image sampler which is
used by the implementation to read image data and apply filtering and other
transformations for the shader.

Samplers are represented by sname:VkSampler handles:

include::{generated}/api/handles/VkSampler.txt[]

--

[open,refpage='vkCreateSampler',desc='Create a new sampler object',type='protos']
--

To create a sampler object, call:

include::{generated}/api/protos/vkCreateSampler.txt[]

  * pname:device is the logical device that creates the sampler.
  * pname:pCreateInfo is a pointer to an instance of the
    slink:VkSamplerCreateInfo structure specifying the state of the sampler
    object.
  * pname:pAllocator controls host memory allocation as described in the
    <<memory-allocation, Memory Allocation>> chapter.
  * pname:pSampler points to a slink:VkSampler handle in which the resulting
    sampler object is returned.

include::{generated}/validity/protos/vkCreateSampler.txt[]
--

[open,refpage='VkSamplerCreateInfo',desc='Structure specifying parameters of a newly created sampler',type='structs']
--

The sname:VkSamplerCreateInfo structure is defined as:

include::{generated}/api/structs/VkSamplerCreateInfo.txt[]

  * pname:sType is the type of this structure.
  * pname:pNext is `NULL` or a pointer to an extension-specific structure.
  * pname:flags is a bitmask of elink:VkSamplerCreateFlagBits describing
    additional parameters of the sampler.
  * pname:magFilter is a elink:VkFilter value specifying the magnification
    filter to apply to lookups.
  * pname:minFilter is a elink:VkFilter value specifying the minification
    filter to apply to lookups.
  * pname:mipmapMode is a elink:VkSamplerMipmapMode value specifying the
    mipmap filter to apply to lookups.
  * pname:addressModeU is a elink:VkSamplerAddressMode value specifying the
    addressing mode for outside [0..1] range for U coordinate.
  * pname:addressModeV is a elink:VkSamplerAddressMode value specifying the
    addressing mode for outside [0..1] range for V coordinate.
  * pname:addressModeW is a elink:VkSamplerAddressMode value specifying the
    addressing mode for outside [0..1] range for W coordinate.
  * [[samplers-mipLodBias]] pname:mipLodBias is the bias to be added to
    mipmap LOD (level-of-detail) calculation and bias provided by image
    sampling functions in SPIR-V, as described in the
    <<textures-level-of-detail-operation, Level-of-Detail Operation>>
    section.
  * [[samplers-maxAnisotropy]] pname:anisotropyEnable is ename:VK_TRUE to
    enable anisotropic filtering, as described in the
    <<textures-texel-anisotropic-filtering, Texel Anisotropic Filtering>>
    section, or ename:VK_FALSE otherwise.
  * pname:maxAnisotropy is the anisotropy value clamp used by the sampler
    when pname:anisotropyEnable is ename:VK_TRUE.
    If pname:anisotropyEnable is ename:VK_FALSE, pname:maxAnisotropy is
    ignored.
  * pname:compareEnable is ename:VK_TRUE to enable comparison against a
    reference value during lookups, or ename:VK_FALSE otherwise.
  ** Note: Some implementations will default to shader state if this member
     does not match.
  * pname:compareOp is a elink:VkCompareOp value specifying the comparison
    function to apply to fetched data before filtering as described in the
    <<textures-depth-compare-operation, Depth Compare Operation>> section.
  * pname:minLod and pname:maxLod are the values used to clamp the computed
    LOD value, as described in the <<textures-level-of-detail-operation,
    Level-of-Detail Operation>> section.
  * pname:borderColor is a elink:VkBorderColor value specifying the
    predefined border color to use.
  * [[samplers-unnormalizedCoordinates]] pname:unnormalizedCoordinates
    controls whether to use unnormalized or normalized texel coordinates to
    address texels of the image.
    When set to ename:VK_TRUE, the range of the image coordinates used to
    lookup the texel is in the range of zero to the image dimensions for x,
    y and z.
    When set to ename:VK_FALSE the range of image coordinates is zero to
    one.
+
When pname:unnormalizedCoordinates is ename:VK_TRUE, images the sampler is
used with in the shader have the following requirements:
+
  ** The pname:viewType must: be either ename:VK_IMAGE_VIEW_TYPE_1D or
     ename:VK_IMAGE_VIEW_TYPE_2D.
  ** The image view must: have a single layer and a single mip level.
+
When pname:unnormalizedCoordinates is ename:VK_TRUE, image built-in
functions in the shader that use the sampler have the following
requirements:
+
  ** The functions must: not use projection.
  ** The functions must: not use offsets.

[NOTE]
.Mapping of OpenGL to Vulkan filter modes
====
pname:magFilter values of ename:VK_FILTER_NEAREST and ename:VK_FILTER_LINEAR
directly correspond to code:GL_NEAREST and code:GL_LINEAR magnification
filters.
pname:minFilter and pname:mipmapMode combine to correspond to the similarly
named OpenGL minification filter of code:GL_minFilter_MIPMAP_mipmapMode
(e.g. pname:minFilter of ename:VK_FILTER_LINEAR and pname:mipmapMode of
ename:VK_SAMPLER_MIPMAP_MODE_NEAREST correspond to
code:GL_LINEAR_MIPMAP_NEAREST).

There are no Vulkan filter modes that directly correspond to OpenGL
minification filters of code:GL_LINEAR or code:GL_NEAREST, but they can: be
emulated using ename:VK_SAMPLER_MIPMAP_MODE_NEAREST, pname:minLod = 0, and
pname:maxLod = 0.25, and using pname:minFilter = ename:VK_FILTER_LINEAR or
pname:minFilter = ename:VK_FILTER_NEAREST, respectively.

Note that using a pname:maxLod of zero would cause
<<textures-texel-filtering,magnification>> to always be performed, and the
pname:magFilter to always be used.
This is valid, just not an exact match for OpenGL behavior.
Clamping the maximum LOD to 0.25 allows the [eq]#{lambda}# value to be
non-zero and minification to be performed, while still always rounding down
to the base level.
If the pname:minFilter and pname:magFilter are equal, then using a
pname:maxLod of zero also works.
====

The maximum number of sampler objects which can: be simultaneously created
on a device is implementation-dependent and specified by the
<<limits-maxSamplerAllocationCount,maxSamplerAllocationCount>> member of the
slink:VkPhysicalDeviceLimits structure.
If pname:maxSamplerAllocationCount is exceeded, fname:vkCreateSampler will
return ename:VK_ERROR_TOO_MANY_OBJECTS.

Since slink:VkSampler is a non-dispatchable handle type, implementations
may: return the same handle for sampler state vectors that are identical.
In such cases, all such objects would only count once against the
pname:maxSamplerAllocationCount limit.

.Valid Usage
****
  * [[VUID-VkSamplerCreateInfo-mipLodBias-01069]]
    The absolute value of pname:mipLodBias must: be less than or equal to
    sname:VkPhysicalDeviceLimits::pname:maxSamplerLodBias
  * [[VUID-VkSamplerCreateInfo-maxLod-01973]]
    pname:maxLod must: be greater than or equal to pname:minLod
  * [[VUID-VkSamplerCreateInfo-anisotropyEnable-01070]]
    If the <<features-samplerAnisotropy,anisotropic sampling>> feature is
    not enabled, pname:anisotropyEnable must: be ename:VK_FALSE
  * [[VUID-VkSamplerCreateInfo-anisotropyEnable-01071]]
    If pname:anisotropyEnable is ename:VK_TRUE, pname:maxAnisotropy must: be
    between `1.0` and
    sname:VkPhysicalDeviceLimits::pname:maxSamplerAnisotropy, inclusive
ifdef::VK_VERSION_1_1,VK_KHR_sampler_ycbcr_conversion[]
  * [[VUID-VkSamplerCreateInfo-minFilter-01645]]
    If <<samplers-YCbCr-conversion,sampler Y'C~B~C~R~ conversion>> is
    enabled and
    ename:VK_FORMAT_FEATURE_SAMPLED_IMAGE_YCBCR_CONVERSION_SEPARATE_RECONSTRUCTION_FILTER_BIT
    is not set for the format, pname:minFilter and pname:magFilter must: be
    equal to the sampler Y'C~B~C~R~ conversion's pname:chromaFilter
endif::VK_VERSION_1_1,VK_KHR_sampler_ycbcr_conversion[]
  * [[VUID-VkSamplerCreateInfo-unnormalizedCoordinates-01072]]
    If pname:unnormalizedCoordinates is ename:VK_TRUE, pname:minFilter and
    pname:magFilter must: be equal
  * [[VUID-VkSamplerCreateInfo-unnormalizedCoordinates-01073]]
    If pname:unnormalizedCoordinates is ename:VK_TRUE, pname:mipmapMode
    must: be ename:VK_SAMPLER_MIPMAP_MODE_NEAREST
  * [[VUID-VkSamplerCreateInfo-unnormalizedCoordinates-01074]]
    If pname:unnormalizedCoordinates is ename:VK_TRUE, pname:minLod and
    pname:maxLod must: be zero
  * [[VUID-VkSamplerCreateInfo-unnormalizedCoordinates-01075]]
    If pname:unnormalizedCoordinates is ename:VK_TRUE, pname:addressModeU
    and pname:addressModeV must: each be either
    ename:VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_EDGE or
    ename:VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_BORDER
  * [[VUID-VkSamplerCreateInfo-unnormalizedCoordinates-01076]]
    If pname:unnormalizedCoordinates is ename:VK_TRUE,
    pname:anisotropyEnable must: be ename:VK_FALSE
  * [[VUID-VkSamplerCreateInfo-unnormalizedCoordinates-01077]]
    If pname:unnormalizedCoordinates is ename:VK_TRUE, pname:compareEnable
    must: be ename:VK_FALSE
  * [[VUID-VkSamplerCreateInfo-addressModeU-01078]]
    If any of pname:addressModeU, pname:addressModeV or pname:addressModeW
    are ename:VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_BORDER, pname:borderColor
    must: be a valid elink:VkBorderColor value
ifdef::VK_VERSION_1_1,VK_KHR_sampler_ycbcr_conversion[]
  * [[VUID-VkSamplerCreateInfo-addressModeU-01646]]
    If <<samplers-YCbCr-conversion,sampler Y'C~B~C~R~ conversion>> is
    enabled, pname:addressModeU, pname:addressModeV, and pname:addressModeW
    must: be ename:VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_EDGE,
    pname:anisotropyEnable must: be ename:VK_FALSE, and
    pname:unnormalizedCoordinates must: be ename:VK_FALSE
ifdef::VK_EXT_sampler_filter_minmax[]
  * [[VUID-VkSamplerCreateInfo-None-01647]]
    The sampler reduction mode must: be set to
    ename:VK_SAMPLER_REDUCTION_MODE_WEIGHTED_AVERAGE_EXT if
    <<samplers-YCbCr-conversion,sampler Y'C~B~C~R~ conversion>> is enabled
endif::VK_EXT_sampler_filter_minmax[]
endif::VK_VERSION_1_1,VK_KHR_sampler_ycbcr_conversion[]
  * [[VUID-VkSamplerCreateInfo-addressModeU-01079]]
    If the `<<VK_KHR_sampler_mirror_clamp_to_edge>>` extension is not
    enabled, pname:addressModeU, pname:addressModeV and pname:addressModeW
    must: not be ename:VK_SAMPLER_ADDRESS_MODE_MIRROR_CLAMP_TO_EDGE
  * [[VUID-VkSamplerCreateInfo-compareEnable-01080]]
    If pname:compareEnable is ename:VK_TRUE, pname:compareOp must: be a
    valid elink:VkCompareOp value
ifdef::VK_IMG_filter_cubic,VK_EXT_filter_cubic[]
  * [[VUID-VkSamplerCreateInfo-magFilter-01081]]
    If either pname:magFilter or pname:minFilter is
    ename:VK_FILTER_CUBIC_EXT, pname:anisotropyEnable must: be
    ename:VK_FALSE
endif::VK_IMG_filter_cubic,VK_EXT_filter_cubic[]
ifdef::VK_IMG_filter_cubic+VK_EXT_sampler_filter_minmax[]
ifndef::VK_EXT_filter_cubic[]
  * [[VUID-VkSamplerCreateInfo-magFilter-01422]]
    If either pname:magFilter or pname:minFilter is
    ename:VK_FILTER_CUBIC_EXT, the pname:reductionMode member of
    slink:VkSamplerReductionModeCreateInfoEXT must: be
    ename:VK_SAMPLER_REDUCTION_MODE_WEIGHTED_AVERAGE_EXT
endif::VK_EXT_filter_cubic[]
endif::VK_IMG_filter_cubic+VK_EXT_sampler_filter_minmax[]
ifdef::VK_EXT_sampler_filter_minmax[]
  * [[VUID-VkSamplerCreateInfo-compareEnable-01423]]
    If pname:compareEnable is ename:VK_TRUE, the pname:reductionMode member
    of slink:VkSamplerReductionModeCreateInfoEXT must: be
    ename:VK_SAMPLER_REDUCTION_MODE_WEIGHTED_AVERAGE_EXT
endif::VK_EXT_sampler_filter_minmax[]
ifdef::VK_EXT_fragment_density_map[]
  * [[VUID-VkSamplerCreateInfo-flags-02574]]
    If pname:flags includes ename:VK_SAMPLER_CREATE_SUBSAMPLED_BIT_EXT, then
    pname:minFilter and pname:magFilter must: be equal.
  * [[VUID-VkSamplerCreateInfo-flags-02575]]
    If pname:flags includes ename:VK_SAMPLER_CREATE_SUBSAMPLED_BIT_EXT, then
    pname:mipmapMode must: be ename:VK_SAMPLER_MIPMAP_MODE_NEAREST.
  * [[VUID-VkSamplerCreateInfo-flags-02576]]
    If pname:flags includes ename:VK_SAMPLER_CREATE_SUBSAMPLED_BIT_EXT, then
    pname:minLod and pname:maxLod must: be zero.
  * [[VUID-VkSamplerCreateInfo-flags-02577]]
    If pname:flags includes ename:VK_SAMPLER_CREATE_SUBSAMPLED_BIT_EXT, then
    pname:addressModeU and pname:addressModeV must: each be either
    ename:VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_EDGE or
    ename:VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_BORDER.
  * [[VUID-VkSamplerCreateInfo-flags-02578]]
    If pname:flags includes ename:VK_SAMPLER_CREATE_SUBSAMPLED_BIT_EXT, then
    pname:anisotropyEnable must: be ename:VK_FALSE.
  * [[VUID-VkSamplerCreateInfo-flags-02579]]
    If pname:flags includes ename:VK_SAMPLER_CREATE_SUBSAMPLED_BIT_EXT, then
    pname:compareEnable must: be ename:VK_FALSE.
  * [[VUID-VkSamplerCreateInfo-flags-02580]]
    If pname:flags includes ename:VK_SAMPLER_CREATE_SUBSAMPLED_BIT_EXT, then
    pname:unnormalizedCoordinates must: be ename:VK_FALSE.
endif::VK_EXT_fragment_density_map[]
****

include::{generated}/validity/structs/VkSamplerCreateInfo.txt[]
--

[open,refpage='VkSamplerCreateFlagBits',desc='Bitmask specifying additional parameters of sampler',type='enums']
--

Bits which can: be set in slink:VkSamplerCreateInfo::pname:flags, specifying
additional parameters of a sampler, are:

include::{generated}/api/enums/VkSamplerCreateFlagBits.txt[]

ifdef::VK_EXT_fragment_density_map[]
  * [[samplers-subsamplesampler]] ename:VK_SAMPLER_CREATE_SUBSAMPLED_BIT_EXT
    specifies that the sampler will read from an image created with
    pname:flags containing ename:VK_IMAGE_CREATE_SUBSAMPLED_BIT_EXT.
  * ename:VK_SAMPLER_CREATE_SUBSAMPLED_COARSE_RECONSTRUCTION_BIT_EXT
    specifies that the implementation may: use approximations when
    reconstructing a full color value for texture access from a subsampled
    image.

[NOTE]
.Note
====
The approximations used when
ename:VK_SAMPLER_CREATE_SUBSAMPLED_COARSE_RECONSTRUCTION_BIT_EXT is
specified are implementation defined.
Some implementations may: interpolate between fragment density levels in a
subsampled image.
In that case, this bit may: be used to decide whether the interpolation
factors are calculated per fragment or at a coarser granularity.
====
endif::VK_EXT_fragment_density_map[]
--

[open,refpage='VkSamplerCreateFlags',desc='Reserved for future use',type='flags']
--
include::{generated}/api/flags/VkSamplerCreateFlags.txt[]

tname:VkSamplerCreateFlags is a bitmask type for setting a mask of zero or
more elink:VkSamplerCreateFlagBits.
--

ifdef::VK_EXT_sampler_filter_minmax[]

[open,refpage='VkSamplerReductionModeCreateInfoEXT',desc='Structure specifying sampler reduction mode',type='structs']
--
If the pname:pNext chain of slink:VkSamplerCreateInfo includes a
sname:VkSamplerReductionModeCreateInfoEXT structure, then that structure
includes a mode that controls how texture filtering combines texel values.

The sname:VkSamplerReductionModeCreateInfoEXT structure is defined as:

include::{generated}/api/structs/VkSamplerReductionModeCreateInfoEXT.txt[]

  * pname:sType is the type of this structure.
  * pname:pNext is `NULL` or a pointer to an extension-specific structure.
  * pname:reductionMode is an enum of type elink:VkSamplerReductionModeEXT
    that controls how texture filtering combines texel values.

If this structure is not present, pname:reductionMode is considered to be
ename:VK_SAMPLER_REDUCTION_MODE_WEIGHTED_AVERAGE_EXT.

include::{generated}/validity/structs/VkSamplerReductionModeCreateInfoEXT.txt[]
--

[open,refpage='VkSamplerReductionModeEXT',desc='Specify reduction mode for texture filtering',type='enums']
--
Reduction modes are specified by elink:VkSamplerReductionModeEXT, which
takes values:

include::{generated}/api/enums/VkSamplerReductionModeEXT.txt[]

  * ename:VK_SAMPLER_REDUCTION_MODE_WEIGHTED_AVERAGE_EXT specifies that
    texel values are combined by computing a weighted average of values in
    the footprint, using weights as specified in
    <<textures-unnormalized-to-integer,the image operations chapter>>.
  * ename:VK_SAMPLER_REDUCTION_MODE_MIN_EXT specifies that texel values are
    combined by taking the component-wise minimum of values in the footprint
    with non-zero weights.
  * ename:VK_SAMPLER_REDUCTION_MODE_MAX_EXT specifies that texel values are
    combined by taking the component-wise maximum of values in the footprint
    with non-zero weights.
--

endif::VK_EXT_sampler_filter_minmax[]

[open,refpage='VkFilter',desc='Specify filters used for texture lookups',type='enums']
--
Possible values of the slink:VkSamplerCreateInfo::pname:magFilter and
pname:minFilter parameters, specifying filters used for texture lookups,
are:

include::{generated}/api/enums/VkFilter.txt[]

  * ename:VK_FILTER_NEAREST specifies nearest filtering.
  * ename:VK_FILTER_LINEAR specifies linear filtering.
ifdef::VK_IMG_filter_cubic,VK_EXT_filter_cubic[]
  * ename:VK_FILTER_CUBIC_EXT specifies cubic filtering.
endif::VK_IMG_filter_cubic,VK_EXT_filter_cubic[]

These filters are described in detail in <<textures-texel-filtering, Texel
Filtering>>.

--

[open,refpage='VkSamplerMipmapMode',desc='Specify mipmap mode used for texture lookups',type='enums']
--

Possible values of the slink:VkSamplerCreateInfo::pname:mipmapMode,
specifying the mipmap mode used for texture lookups, are:

include::{generated}/api/enums/VkSamplerMipmapMode.txt[]

  * ename:VK_SAMPLER_MIPMAP_MODE_NEAREST specifies nearest filtering.
  * ename:VK_SAMPLER_MIPMAP_MODE_LINEAR specifies linear filtering.

These modes are described in detail in <<textures-texel-filtering, Texel
Filtering>>.

--

[open,refpage='VkSamplerAddressMode',desc='Specify behavior of sampling with texture coordinates outside an image',type='enums']
--

Possible values of the slink:VkSamplerCreateInfo::ptext:addressMode*
parameters, specifying the behavior of sampling with coordinates outside the
range [eq]#[0,1]# for the respective [eq]#u#, [eq]#v#, or [eq]#w# coordinate
as defined in the <<textures-wrapping-operation, Wrapping Operation>>
section, are:

include::{generated}/api/enums/VkSamplerAddressMode.txt[]

  * ename:VK_SAMPLER_ADDRESS_MODE_REPEAT specifies that the repeat wrap mode
    will be used.
  * ename:VK_SAMPLER_ADDRESS_MODE_MIRRORED_REPEAT specifies that the
    mirrored repeat wrap mode will be used.
  * ename:VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_EDGE specifies that the clamp to
    edge wrap mode will be used.
  * ename:VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_BORDER specifies that the clamp
    to border wrap mode will be used.
  * ename:VK_SAMPLER_ADDRESS_MODE_MIRROR_CLAMP_TO_EDGE specifies that the
    mirror clamp to edge wrap mode will be used.
    This is only valid if the `<<VK_KHR_sampler_mirror_clamp_to_edge>>`
    extension is enabled.

--

[open,refpage='VkBorderColor',desc='Specify border color used for texture lookups',type='enums']
--

Possible values of slink:VkSamplerCreateInfo::pname:borderColor, specifying
the border color used for texture lookups, are:

include::{generated}/api/enums/VkBorderColor.txt[]

  * ename:VK_BORDER_COLOR_FLOAT_TRANSPARENT_BLACK specifies a transparent,
    floating-point format, black color.
  * ename:VK_BORDER_COLOR_INT_TRANSPARENT_BLACK specifies a transparent,
    integer format, black color.
  * ename:VK_BORDER_COLOR_FLOAT_OPAQUE_BLACK specifies an opaque,
    floating-point format, black color.
  * ename:VK_BORDER_COLOR_INT_OPAQUE_BLACK specifies an opaque, integer
    format, black color.
  * ename:VK_BORDER_COLOR_FLOAT_OPAQUE_WHITE specifies an opaque,
    floating-point format, white color.
  * ename:VK_BORDER_COLOR_INT_OPAQUE_WHITE specifies an opaque, integer
    format, white color.

These colors are described in detail in <<textures-texel-replacement, Texel
Replacement>>.

--

[open,refpage='vkDestroySampler',desc='Destroy a sampler object',type='protos']
--

To destroy a sampler, call:

include::{generated}/api/protos/vkDestroySampler.txt[]

  * pname:device is the logical device that destroys the sampler.
  * pname:sampler is the sampler to destroy.
  * pname:pAllocator controls host memory allocation as described in the
    <<memory-allocation, Memory Allocation>> chapter.

.Valid Usage
****
  * [[VUID-vkDestroySampler-sampler-01082]]
    All submitted commands that refer to pname:sampler must: have completed
    execution
  * [[VUID-vkDestroySampler-sampler-01083]]
    If sname:VkAllocationCallbacks were provided when pname:sampler was
    created, a compatible set of callbacks must: be provided here
  * [[VUID-vkDestroySampler-sampler-01084]]
    If no sname:VkAllocationCallbacks were provided when pname:sampler was
    created, pname:pAllocator must: be `NULL`
****

include::{generated}/validity/protos/vkDestroySampler.txt[]
--


ifdef::VK_VERSION_1_1,VK_KHR_sampler_ycbcr_conversion[]

[[samplers-YCbCr-conversion]]
== Sampler Y'C~B~C~R~ conversion

[open,refpage='VkSamplerYcbcrConversionInfo',desc='Structure specifying Y\'CbCr conversion to a sampler or image view',type='structs']
--

To create a sampler with Y'C~B~C~R~ conversion enabled, add a
slink:VkSamplerYcbcrConversionInfo to the pname:pNext chain of the
slink:VkSamplerCreateInfo structure.
To create a sampler Y'C~B~C~R~ conversion, the
<<features-sampler-YCbCr-conversion,pname:samplerYcbcrConversion feature>>
must: be enabled.
Conversion must: be fixed at pipeline creation time, through use of a
combined image sampler with an immutable sampler in
sname:VkDescriptorSetLayoutBinding.

A slink:VkSamplerYcbcrConversionInfo must: be provided for samplers to be
used with image views that access ename:VK_IMAGE_ASPECT_COLOR_BIT if the
format appears in <<formats-requiring-sampler-ycbcr-conversion>>
ifdef::VK_ANDROID_external_memory_android_hardware_buffer[]
, or if the image view has an
<<memory-external-android-hardware-buffer-external-formats,external format>>
endif::VK_ANDROID_external_memory_android_hardware_buffer[]
.

The sname:VkSamplerYcbcrConversionInfo structure is defined as:

include::{generated}/api/structs/VkSamplerYcbcrConversionInfo.txt[]

ifdef::VK_KHR_sampler_ycbcr_conversion[]
or the equivalent

include::{generated}/api/structs/VkSamplerYcbcrConversionInfoKHR.txt[]
endif::VK_KHR_sampler_ycbcr_conversion[]

  * pname:sType is the type of this structure.
  * pname:pNext is `NULL` or a pointer to an extension-specific structure.
  * pname:conversion is a slink:VkSamplerYcbcrConversion handle created with
    flink:vkCreateSamplerYcbcrConversion.

include::{generated}/validity/structs/VkSamplerYcbcrConversionInfo.txt[]

--

[open,refpage='VkSamplerYcbcrConversion',desc='Opaque handle to a device-specific sampler Y\'C~B~C~R~ conversion description',type='handles']
--

A sampler Y'C~B~C~R~ conversion is an opaque representation of a
device-specific sampler Y'C~B~C~R~ conversion description, represented as a
sname:VkSamplerYcbcrConversion handle:

include::{generated}/api/handles/VkSamplerYcbcrConversion.txt[]

ifdef::VK_KHR_sampler_ycbcr_conversion[]
or the equivalent

include::{generated}/api/handles/VkSamplerYcbcrConversionKHR.txt[]
endif::VK_KHR_sampler_ycbcr_conversion[]

--

[open,refpage='vkCreateSamplerYcbcrConversion',desc='Create a new Ycbcr conversion',type='protos']
--

To create a slink:VkSamplerYcbcrConversion, call:

ifdef::VK_VERSION_1_1[]
include::{generated}/api/protos/vkCreateSamplerYcbcrConversion.txt[]
endif::VK_VERSION_1_1[]

ifdef::VK_VERSION_1_1+VK_KHR_sampler_ycbcr_conversion[or the equivalent command]

ifdef::VK_KHR_sampler_ycbcr_conversion[]
include::{generated}/api/protos/vkCreateSamplerYcbcrConversionKHR.txt[]
endif::VK_KHR_sampler_ycbcr_conversion[]

  * pname:device is the logical device that creates the sampler Y'C~B~C~R~
    conversion.
  * pname:pCreateInfo is a pointer to an instance of the
    slink:VkSamplerYcbcrConversionCreateInfo specifying the requested
    sampler Y'C~B~C~R~ conversion.
  * pname:pAllocator controls host memory allocation as described in the
    <<memory-allocation, Memory Allocation>> chapter.
  * pname:pYcbcrConversion points to a slink:VkSamplerYcbcrConversion handle
    in which the resulting sampler Y'C~B~C~R~ conversion is returned.

The interpretation of the configured sampler Y'C~B~C~R~ conversion is
described in more detail in <<textures-sampler-YCbCr-conversion,the
description of sampler Y'C~B~C~R~ conversion>> in the <<textures,Image
Operations>> chapter.

.Valid Usage
****
  * [[VUID-vkCreateSamplerYcbcrConversion-None-01648]]
    The <<features-sampler-YCbCr-conversion, sampler Y'C~B~C~R~ conversion
    feature>> must: be enabled
****

include::{generated}/validity/protos/vkCreateSamplerYcbcrConversion.txt[]

--

[open,refpage='VkSamplerYcbcrConversionCreateInfo',desc='Structure specifying the parameters of the newly created conversion',type='structs']
--

The sname:VkSamplerYcbcrConversionCreateInfo structure is defined as:

include::{generated}/api/structs/VkSamplerYcbcrConversionCreateInfo.txt[]

ifdef::VK_KHR_sampler_ycbcr_conversion[]
or the equivalent

include::{generated}/api/structs/VkSamplerYcbcrConversionCreateInfoKHR.txt[]
endif::VK_KHR_sampler_ycbcr_conversion[]

  * pname:sType is the type of this structure.
  * pname:pNext is `NULL` or a pointer to an extension-specific structure.
  * pname:format is the format of the image from which color information
    will be retrieved.
  * pname:ycbcrModel describes the color matrix for conversion between color
    models.
  * pname:ycbcrRange describes whether the encoded values have headroom and
    foot room, or whether the encoding uses the full numerical range.
  * pname:components applies a _swizzle_ based on elink:VkComponentSwizzle
    enums prior to range expansion and color model conversion.
  * pname:xChromaOffset describes the
    <<textures-chroma-reconstruction,sample location>> associated with
    downsampled chroma channels in the x dimension.
    pname:xChromaOffset has no effect for formats in which chroma channels
    are the same resolution as the luma channel.
  * pname:yChromaOffset describes the
    <<textures-chroma-reconstruction,sample location>> associated with
    downsampled chroma channels in the y dimension.
    pname:yChromaOffset has no effect for formats in which the chroma
    channels are not downsampled vertically.
  * pname:chromaFilter is the filter for chroma reconstruction.
  * pname:forceExplicitReconstruction can: be used to ensure that
    reconstruction is done explicitly, if supported.

[NOTE]
.Note
====
Setting pname:forceExplicitReconstruction to ename:VK_TRUE may: have a
performance penalty on implementations where explicit reconstruction is not
the default mode of operation.
====

ifdef::VK_ANDROID_external_memory_android_hardware_buffer[]
If the pname:pNext chain has an instance of slink:VkExternalFormatANDROID
with non-zero pname:externalFormat member, the sampler Y'C~B~C~R~ conversion
object represents an _external format conversion_, and pname:format must: be
ename:VK_FORMAT_UNDEFINED.
Such conversions must: only be used to sample image views with a matching
<<memory-external-android-hardware-buffer-external-formats,external
format>>.
When creating an external format conversion, the value of pname:components
is ignored.
endif::VK_ANDROID_external_memory_android_hardware_buffer[]
ifndef::VK_ANDROID_external_memory_android_hardware_buffer[]
Sampler Y'C~B~C~R~ conversion objects do not support _external format
conversion_ without additional extensions defining _external formats_.
endif::VK_ANDROID_external_memory_android_hardware_buffer[]

.Valid Usage
****
ifndef::VK_ANDROID_external_memory_android_hardware_buffer[]
  * [[VUID-VkSamplerYcbcrConversionCreateInfo-format-01649]]
    pname:format must: not be ename:VK_FORMAT_UNDEFINED
endif::VK_ANDROID_external_memory_android_hardware_buffer[]
ifdef::VK_ANDROID_external_memory_android_hardware_buffer[]
  * [[VUID-VkSamplerYcbcrConversionCreateInfo-format-01904]]
    If an external format conversion is being created, pname:format must: be
    ename:VK_FORMAT_UNDEFINED, otherwise it must: not be
    ename:VK_FORMAT_UNDEFINED.
endif::VK_ANDROID_external_memory_android_hardware_buffer[]
  * [[VUID-VkSamplerYcbcrConversionCreateInfo-format-01650]]
    pname:format must: support
    ename:VK_FORMAT_FEATURE_MIDPOINT_CHROMA_SAMPLES_BIT or
    ename:VK_FORMAT_FEATURE_COSITED_CHROMA_SAMPLES_BIT
  * [[VUID-VkSamplerYcbcrConversionCreateInfo-xChromaOffset-01651]]
    If the format does not support
    ename:VK_FORMAT_FEATURE_COSITED_CHROMA_SAMPLES_BIT, pname:xChromaOffset
    and pname:yChromaOffset must: not be
    ename:VK_CHROMA_LOCATION_COSITED_EVEN
  * [[VUID-VkSamplerYcbcrConversionCreateInfo-xChromaOffset-01652]]
    If the format does not support
    ename:VK_FORMAT_FEATURE_MIDPOINT_CHROMA_SAMPLES_BIT, pname:xChromaOffset
    and pname:yChromaOffset must: not be ename:VK_CHROMA_LOCATION_MIDPOINT
  * [[VUID-VkSamplerYcbcrConversionCreateInfo-format-01653]]
    pname:format must: represent unsigned normalized values (i.e. the format
    must be a etext:UNORM format)
  * [[VUID-VkSamplerYcbcrConversionCreateInfo-components-02581]]
    If the format has a etext:_422 or etext:_420 suffix, then
    pname:components.g must: be ename:VK_COMPONENT_SWIZZLE_IDENTITY
  * [[VUID-VkSamplerYcbcrConversionCreateInfo-components-02582]]
    If the format has a etext:_422 or etext:_420 suffix, then
    pname:components.a must: be ename:VK_COMPONENT_SWIZZLE_IDENTITY,
    ename:VK_COMPONENT_SWIZZLE_ONE, or ename:VK_COMPONENT_SWIZZLE_ZERO
  * [[VUID-VkSamplerYcbcrConversionCreateInfo-components-02583]]
    If the format has a etext:_422 or etext:_420 suffix, then
    pname:components.r must: be ename:VK_COMPONENT_SWIZZLE_IDENTITY or
    ename:VK_COMPONENT_SWIZZLE_B
  * [[VUID-VkSamplerYcbcrConversionCreateInfo-components-02584]]
    If the format has a etext:_422 or etext:_420 suffix, then
    pname:components.b must: be ename:VK_COMPONENT_SWIZZLE_IDENTITY or
    ename:VK_COMPONENT_SWIZZLE_R
  * [[VUID-VkSamplerYcbcrConversionCreateInfo-components-02585]]
    If the format has a etext:_422 or etext:_420 suffix, and if either
    pname:components.r or pname:components.b is
    ename:VK_COMPONENT_SWIZZLE_IDENTITY, both values must: be
    ename:VK_COMPONENT_SWIZZLE_IDENTITY
  * [[VUID-VkSamplerYcbcrConversionCreateInfo-ycbcrModel-01655]]
    If pname:ycbcrModel is not
    ename:VK_SAMPLER_YCBCR_MODEL_CONVERSION_RGB_IDENTITY, then
    pname:components.r, pname:components.g, and pname:components.b must:
    correspond to channels of the pname:format; that is, pname:components.r,
    pname:components.g, and pname:components.b must: not be
    ename:VK_COMPONENT_SWIZZLE_ZERO or ename:VK_COMPONENT_SWIZZLE_ONE, and
    must: not correspond to a channel which contains zero or one as a
    consequence of <<textures-conversion-to-rgba,conversion to RGBA>>
  * [[VUID-VkSamplerYcbcrConversionCreateInfo-forceExplicitReconstruction-01656]]
    If the format does not support
    ename:VK_FORMAT_FEATURE_SAMPLED_IMAGE_YCBCR_CONVERSION_CHROMA_RECONSTRUCTION_EXPLICIT_FORCEABLE_BIT,
    pname:forceExplicitReconstruction must: be FALSE
  * [[VUID-VkSamplerYcbcrConversionCreateInfo-chromaFilter-01657]]
    If the format does not support
    ename:VK_FORMAT_FEATURE_SAMPLED_IMAGE_YCBCR_CONVERSION_LINEAR_FILTER_BIT,
    pname:chromaFilter must: be ename:VK_FILTER_NEAREST
****

include::{generated}/validity/structs/VkSamplerYcbcrConversionCreateInfo.txt[]

If pname:chromaFilter is ename:VK_FILTER_NEAREST, chroma samples are
reconstructed to luma channel resolution using nearest-neighbour sampling.
Otherwise, chroma samples are reconstructed using interpolation.
More details can be found in <<textures-sampler-YCbCr-conversion,the
description of sampler Y'C~B~C~R~ conversion>> in the <<textures,Image
Operations>> chapter.

--

[open,refpage='VkSamplerYcbcrModelConversion',desc='Color model component of a color space',type='enums']
--

elink:VkSamplerYcbcrModelConversion defines the conversion from the source
color model to the shader color model.
Possible values are:

include::{generated}/api/enums/VkSamplerYcbcrModelConversion.txt[]

ifdef::VK_KHR_sampler_ycbcr_conversion[]
or the equivalent

include::{generated}/api/enums/VkSamplerYcbcrModelConversionKHR.txt[]
endif::VK_KHR_sampler_ycbcr_conversion[]

  * ename:VK_SAMPLER_YCBCR_MODEL_CONVERSION_RGB_IDENTITY specifies that the
    input values to the conversion are unmodified.
  * ename:VK_SAMPLER_YCBCR_MODEL_CONVERSION_YCBCR_IDENTITY specifies no
    model conversion but the inputs are range expanded as for Y'C~B~C~R~.
  * ename:VK_SAMPLER_YCBCR_MODEL_CONVERSION_YCBCR_709 specifies the color
    model conversion from Y'C~B~C~R~ to R'G'B' defined in BT.709 and
    described in the "`BT.709 Y’C~B~C~R~ conversion`" section of the
    <<data-format,Khronos Data Format Specification>>.
  * ename:VK_SAMPLER_YCBCR_MODEL_CONVERSION_YCBCR_601 specifies the color
    model conversion from Y'C~B~C~R~ to R'G'B' defined in BT.601 and
    described in the "`BT.601 Y’C~B~C~R~ conversion`" section of the
    <<data-format,Khronos Data Format Specification>>.
  * ename:VK_SAMPLER_YCBCR_MODEL_CONVERSION_YCBCR_2020 specifies the color
    model conversion from Y'C~B~C~R~ to R'G'B' defined in BT.2020 and
    described in the "`BT.2020 Y’C~B~C~R~ conversion`" section of the
    <<data-format,Khronos Data Format Specification>>.

In the etext:VK_SAMPLER_YCBCR_MODEL_CONVERSION_YCBCR_* color models, for the
input to the sampler Y'C~B~C~R~ range expansion and model conversion:

  * the Y (Y' luma) channel corresponds to the G channel of an RGB image.
  * the CB (C~B~ or "`U`" blue color difference) channel corresponds to the
    B channel of an RGB image.
  * the CR (C~R~ or "`V`" red color difference) channel corresponds to the R
    channel of an RGB image.
  * the alpha channel, if present, is not modified by color model
    conversion.

These rules reflect the mapping of channels after the channel swizzle
operation (controlled by
slink:VkSamplerYcbcrConversionCreateInfo::pname:components).

[NOTE]
.Note
====
For example, an "`YUVA`" 32-bit format comprising four 8-bit channels can be
implemented as ename:VK_FORMAT_R8G8B8A8_UNORM with a component mapping:

  * pname:components.a = ename:VK_COMPONENT_SWIZZLE_IDENTITY
  * pname:components.r = ename:VK_COMPONENT_SWIZZLE_B
  * pname:components.g = ename:VK_COMPONENT_SWIZZLE_R
  * pname:components.b = ename:VK_COMPONENT_SWIZZLE_G
====

--

[open,refpage='VkSamplerYcbcrRange',desc='Range of encoded values in a color space',type='enums']
--

The elink:VkSamplerYcbcrRange enum describes whether color channels are
encoded using the full range of numerical values or whether values are
reserved for headroom and foot room.
elink:VkSamplerYcbcrRange is defined as:

include::{generated}/api/enums/VkSamplerYcbcrRange.txt[]

ifdef::VK_KHR_sampler_ycbcr_conversion[]
or the equivalent

include::{generated}/api/enums/VkSamplerYcbcrRangeKHR.txt[]
endif::VK_KHR_sampler_ycbcr_conversion[]

  * ename:VK_SAMPLER_YCBCR_RANGE_ITU_FULL specifies that the full range of
    the encoded values are valid and interpreted according to the ITU "`full
    range`" quantization rules.
  * ename:VK_SAMPLER_YCBCR_RANGE_ITU_NARROW specifies that headroom and foot
    room are reserved in the numerical range of encoded values, and the
    remaining values are expanded according to the ITU "`narrow range`"
    quantization rules.

The formulae for these conversions is described in the
<<textures-sampler-YCbCr-conversion-rangeexpand,Sampler Y'C~B~C~R~ Range
Expansion>> section of the <<textures,Image Operations>> chapter.

No range modification takes place if pname:ycbcrModel is
ename:VK_SAMPLER_YCBCR_MODEL_CONVERSION_RGB_IDENTITY; the pname:ycbcrRange
field of sname:VkSamplerYcbcrConversionCreateInfo is ignored in this case.

--

[open,refpage='VkChromaLocation',desc='Position of downsampled chroma samples',type='enums']
--

The elink:VkChromaLocation enum, which defines the location of downsampled
chroma channel samples relative to the luma samples, is defined as:

include::{generated}/api/enums/VkChromaLocation.txt[]

ifdef::VK_KHR_sampler_ycbcr_conversion[]
or the equivalent

include::{generated}/api/enums/VkChromaLocationKHR.txt[]
endif::VK_KHR_sampler_ycbcr_conversion[]

  * ename:VK_CHROMA_LOCATION_COSITED_EVEN specifies that downsampled chroma
    samples are aligned with luma samples with even coordinates.
  * ename:VK_CHROMA_LOCATION_MIDPOINT specifies that downsampled chroma
    samples are located half way between each even luma sample and the
    nearest higher odd luma sample.

--

[open,refpage='vkDestroySamplerYcbcrConversion',desc='Destroy a created Y\'CbCr conversion',type='protos']
--

To destroy a sampler Y'C~B~C~R~ conversion, call:

ifdef::VK_VERSION_1_1[]
include::{generated}/api/protos/vkDestroySamplerYcbcrConversion.txt[]
endif::VK_VERSION_1_1[]

ifdef::VK_VERSION_1_1+VK_KHR_sampler_ycbcr_conversion[or the equivalent command]

ifdef::VK_KHR_sampler_ycbcr_conversion[]
include::{generated}/api/protos/vkDestroySamplerYcbcrConversionKHR.txt[]
endif::VK_KHR_sampler_ycbcr_conversion[]

  * pname:device is the logical device that destroys the Y'C~B~C~R~
    conversion.
  * pname:ycbcrConversion is the conversion to destroy.
  * pname:pAllocator controls host memory allocation as described in the
    <<memory-allocation, Memory Allocation>> chapter.

include::{generated}/validity/protos/vkDestroySamplerYcbcrConversion.txt[]

--

endif::VK_VERSION_1_1,VK_KHR_sampler_ycbcr_conversion[]